A desired feature for fluid and gas supply systems is to provide fluid and/or gas flows within the system, particularly at system outlets, that can be maintained at pre-determined temperatures, flow rates and/or total volumes. For example, in residential plumbing systems, it is desirable to deliver fluid at system outlets, for example at a shower head, sink outlet, or appliance intake, at a stable, user-defined temperature, flow rate, and/or volume. Similarly, in commercial plumbing systems, such as those found in laboratories, medical facilities, aquacultural facilities, nurseries, manufacturing facilities, restaurants, hotels, and the like, it is desirable to provide fluid flows within the plumbing system and/or at system outlets that are maintained at a pre-selected temperature, flow rate, and/or volume.
Conventional supply systems that rely on manual valve mechanisms to adjust fluid flow rates and temperatures generally suffer undesirable fluctuations in temperature and flow values due to changes in demand/supply within the system. Initial fluctuations are attributable in large part to inadequate control devices, for example input and valve regulatory mechanisms. In this context, standard residential plumbing systems generally exhibit initial fluctuations of temperature and flow at system outlets due to insensitivity and/or overadjustment of user operated valves (eg., outlet controls for hot and cold water delivery). Moreover, even after desired temperature and flow values have been initially set by the user, swings in temperature and flow may continue to arise during use as a function of supply changes (eg., depletion of hot water) and remote demands (eg., initiation or cessation of demand by a second user) within the water system are a familiar occurrence. Thus, in the past it has been necessary to frequently manipulate system input controls and to tolerate reflexive changes and attendant delays for system equilibration in order to set and maintain desired temperature and flow values.
Despite the long persistence of these problems, current input and mixing systems for controlling fluid and gas temperature and flow rates fail to provide a full range of adequate solutions. For example, in most residential and commercial plumbing systems, devices and methods for controlling fluid temperature and flow at outlets still involve conventional hot and cold water valves. These are manually adjusted to independently regulate flow from the hot and cold water lines through the output. However, the tasks of manually initiating two valves or, optionally, a single valve with two inputs and one output, to select a desired flow rate and temperature, manually testing initial flow and temperature, and fine-tuning the valves to maintain desired flow and temperature, is time consuming and can expose the user to extreme, even dangerous, temperatures and flows. These problems are particularly notable in fluid supply systems having more than one outlet, such as in residential supply systems, were remote fluid demands by appliances or other users contribute to the frequency and range of temperature and flow fluctuations.
More advanced input and mixing devices for fluid and gas supply systems incorporate electronic input and control mechanisms to regulate fluid or gas temperature and flow. In this context, a variety of designs have been proposed for electronic-controlled mixing of hot and cold fluids to produce a mixed fluid having a preselected temperature. Many of those proposed systems utilize analog circuitry to provide a feedback control algorithm. For example, U.S. Pat. No. 4,359,186 issued to Kiendel discloses a mixing valve arrangement employing motor driven valves to supply hot and cold water to a mixing chamber. Temperature of the water in the mixing chamber is measured and is used, along with the flow rate of fluid moving through the mixing chamber, in an analog control circuit that provides signals to control the valve motors in response to temperature variations. However, this type of temperature control system is relatively inflexible, and, in order to adjust control constants or change the control algorithm, circuit components must be physically replaced or adjusted.
Other proposed fluid and gas control systems incorporate a digital processor, such as a microcomputer, for implementing a control algorithm. For example, U.S. Pat. No. 4,420,811 issued to Tarnay et al. discloses a water temperature control system in which a feedback control algorithm is implemented by a microcomputer. However, the valve arrangement, configuration of the water discharge channel, and the temperature sensor device of this system are not specifically directed to achieving rapid and accurate temperature and flow responses.
A more advanced fluid temperature control system is disclosed in U.S. Pat. No. 5,050,062 issued to Hass. This system uses a microcomputer coupled with a temperature sensor to provide automatic control of hot and cold supply valves, whereby a fluid mixture discharged from the system can be maintained at a preselected temperature within pre-determined limits. The fluid temperature control system actively mixes hot and cold fluids using together before measuring the temperature of the fluid mixture. Mixing of the fluids takes place in a special mixing chamber and is controlled for each of the hot and cold valves by a separate stepper motor connected therewith. The stepper motors move the respective valve members to regulate hot and cold fluid flow into the mixing chamber.
To control fluid mixing within this system, a temperature sensor is connected to the system outlet connection and is adapted to generates an analog signal corresponding to an actual temperature of the mixed fluid in the outlet connection. The analog temperature signal is amplified and conditioned, and thereafter converted into a digital temperature signal corresponding to the actual temperature of the mixed fluid. The digitized signal from the converter is sent to the microprocessor which is programmed to use the digitized temperature signal within a feedback control algorithm to generate control signals for the stepper motors to regulate the hot and cold supply valves to cause the actual temperature of the mixed fluid to approach the preselected temperature. In more detailed embodiments, the system allows for entry of a selected set point temperature by a user inputting the selection into a programmable microprocessor, for example by means of a keypad or remote computer connected to the processor. Also provided is a display for indicating system parameters, including the set point and actual temperatures of mixed fluid, and a selected flow rate.
Other proposed fluid control systems also incorporate a microcomputer for automatically adjusting fluid system parameters. In this regard, U.S. Pat. No. 5,170,361 issued to Reed et al. discloses a similar control system to that set forth in the Haas patent, supra. However, system parameters which are monitored and maintained to closely approximate user selections via the microprocessor include temperature, flow rate, and volume. This system also features first and second valves to regulate fluid flow from two supplies (eg., hot and cold), along with sensing means to sense open or closed positions for each valve. Also provided are means for activating the first and second valves to regulate their discharge into a dispensing pipe. Other sensors include mixed flow and temperature sensors.
The system of Reed also features a user input that provides for termination of hot and/or cold fluid flow, and for selection of mixed fluid flow rate and temperature. A processor receives data from the sensors (valve, temperature, and flow) and provides a signal to control the valve activating means, to adjust the mixed fluid flow rate and temperature. Also provided is a user display that shows system status information, and a remote control capability including a portable control unit or personal computer linked to the control panel.
Another electronically controlled fluid delivery system is described in U.S. Pat. No. 4,682,728 issued to Oudenhoven et al. This system uses a multi-port valve and stepper motor to control the volume ratio of two fluids, eg., hot and cold water. Mixed water passes through a flow rate control valve disposed near the outlet port controlled by a separate stepper motor. To maintain a selected temperature and flow rate, the user may input selections, eg., via a keypad, into the control unit, which selections may subsequently be recalled by the user from the control unit's memory. The control unit also receives input signals from a temperature sensor, compares the sensed temperature to the user-selected temperature stored in the control unit, and signals the stepper motors for the temperature and flow control valves to regulate system parameters. Also provided is a display unit that signals when the desired temperature has been reached.
Additional features include a maximum temperature shut off safety, and an auxiliary power source to maintain system operability during power outage.
Yet another electronically controlled fluid delivery system is described in U.S. Pat. No. 4,696,428 issued to Shakalis. This system features a dual temperature mixing valve controlled by a mixing valve actuator. Mixed fluid flows through a volume control valve and is sampled by a temperature sensor and flow sensor prior to exiting the outlet. The sensors signal a controller unit which interprets the signals and outputs corrective signals to the mixing valve actuator and volume control valve to adjust temperature and flow rate to approximate user-selected values. A user interface allows user selection of system parameters, eg., to allow selection of a constant temperature via a keyboard operably connected to the controller, and also displays system parameters (eg., temperature and flow rate).
While the foregoing, electronic fluid control systems overcome many of the problems that attend conventional plumbing and manufacturing systems, these systems nonetheless suffer a variety of drawbacks in terms of cost, complexity of installation and operation, range and flexibility of functions, and other attributes. Each of the systems outlined above suffer to some degree from these common shortcomings. Moreover, among the electronic fluid and gas supply systems heretofore proposed, a variety of desirable features that would add yet additional desired functions and uses have not been developed.
Therefore, it is an object of the present invention to provide a fluid and gas control system which is easily operated and which provides for user selection, memory storage and recall, and accurate system maintenance, of a broad range of supply parameters including pre-determined temperatures, flow rates, periods of flow, and volumes.
It is a further object of the invention to achieve the foregoing objects in a fluid and gas control system which can be incorporated within both residential and commercial supply systems, the latter including medical facilities, scientific and photographic laboratories, aquacultural facilities, nurseries, manufacturing plants, chemical plants, restaurants, hotels and the like.